The present invention relates to a self-adjusting device for adjusting the length of control cables which, particularly, have steel cables provided with a sheath usually used in control and adjusting mechanisms and, in particular, in the automobile industry.
The use of self-adjusting devices which are disposed on the control cable itself and serve to adjust and set the length of sheathed steel cable extending between the mechanisms connected thereby is widely known in the automobile industry. The devices are used for example, in control cables for the clutch mechanism, the gear change mechanism, etc.
The purpose of the self-adjusting devices is to take up the tolerances in the distance between the points of connection of the control cables of the mechanisms connected thereby, during the assembly process of each vehicle in particular. Thereby the length of the control cables are adjusted and set precisely while they are being assembled in the vehicle.
Under these conditions, the control cables usually comprise, in addition to the regular connection terminals, a self-adjusting device allowing normally automatical adjustment of the length of the control cable in the portion where the steel cable is sheathed, once said control cable has been connected at both ends thereof to the corresponding mechanisms.
In this way, the known of control cable length self-adjusting devices comprise all or some of the following operative members. The devices have a main body member through which and adjusting stud may suitably slide. This is provided with a retaining screw thread and is firmly attached at one end to the sheath, of the steel cable. The cable, stripped of its sheath, may slide longitudinally through the adjusting stud. The main body member is provided with mechanical means allowing it to be attached to a fixed point of the motor vehicle structure. The devices also have retaining means disposed inside the main body member. These means operate on the adjusting stud so as to set the position thereof relative to the said fixed point.
The devices further have a control spring coaxially disposed relative to the adjusting stud. This spring bears permanently against the main body member and against the adjusting stud at the end attached to the steel cable sheath.
The above described self-adjusting devices are supplied originally with the control spring compressed. When both ends of the control cable ar attached to the points of connection of the mechanisms the cable joins together and the device main body member is attached to a fixed point on the vehicle structure, the adjusting stud is released from the retaining means and under the urging of the control spring it establishes the appropriate length of the sheathed cable between the adjusting stud and the corresponding mechanism. Thereafter the position of the adjusting stud is fixed again with the retaining means with the cable length being appropriately set in this way.
As an example of said control cable length self-adjusting devices, there may be cited Spanish patent P 8803905 for "Control cable tension self-adjusting device" which, providing the innovating features characterizing it, comprises all the operative elements succinctly described above.
Generally speaking, the known control cable length self-adjusting devices have as a main drawback the need to have recourse to tools for actuating the retaining means operating on the adjusting stud during the above described operations of adjusting and setting the control cable length. This causes notable difficulties which increase the cost of installation of the control cables, particularly in those cases in which the self-adjusting device is located, due to the design and/or location of the devices connected by the control cable, in points of the motor vehicle structure of difficult or limited access where the use of tools under appropriate conditions is not feasible.
The control cable length self-adjusting device of the invention has: a main body member suitably dimensioned snugly to house the mechanical retaining means operating on the adjusting stud disposed therethrough and having means allowing it to be attached to a fixed point of the motor vehicle structure; a adjusting stud externally formed with a retaining thread suitably dimensioned relative to the compressive or tensile stress to which it is subjected and which is dimensioned at one end thereof snugly to receive the end of the sheath of the steel cable to which it is firmly attached, said steel cable being capable of sliding, suitably stripped of the sheath, longitudinally through the adjusting stud, having at said end a perimetral flange against which the control spring bears; a control spring which, coaxially disposed relative to the adjusting stud bears permanently against the main body member and against the perimetral flange of the adjusting stud; wherein the main body member is essentially parallelepipedic, hollow, open on two opposite sides and formed, on one side thereof, with a through hole spaced apart at an appropriate distance to a centered perpendicular extension through the inner bore of which the adjusting stud may suitably slide and which is extended externally over a sufficient distance and the dimensions and external shape of which allow attachment of the main body member to a fixed point of the motor vehicle structure and, on the side opposite to the former, two spaced apart through holes respectively facing the said through holes and corresponding recessed portions, in the interior of the main body member at the free end closest to the said extension and on the two remaining faces.
The retaining means operating on the adjusting stud, which as has been described above are housed in the main body member, are formed by actuating means; a hollow, essentially parallelepipedic retaining body member open on two opposite sides and dimensioned so as to be able to slide snugly within the main body member and formed, at one longitudinal end thereof, with two opposite transverse notches defining corresponding angularly disposed fins dimensioned in correspondence with the recessed portions formed in the interior of the main body member and in which they are housed to act as a spring thereagainst, and internally, two facing projections which suitably disposed and dimensioned define respective housings, the one closer to the said transverse notches designed to allow snug passage therethrough of the adjusting stud and the other snugly to house a retaining spring and the actuating means; and an essentially parallelepipedic retaining spring having two extensions formed on two opposite sides thereof and which in angular disposition bear against the said facing projections, the retaining body member and the retaining spring having on the opposite faces thereof respective retaining threads dimensioned in correspondence with the retaining thread formed on the adjusting stud.
The actuating means comprise an actuating shaft which, suitably snugly disposed through the interior of the main body member and of the retaining body member, is prevented from sliding longitudinally by the action of a perimetral flange which is formed on the corresponding free end as a retainer and which is formed on the portion of the shaft positioned in the interior of the main body member and of the retaining body member with two diametral shoulders of suitable dimensions, either of which may act on the retaining spring so that the rotation of said shaft in a sufficient angular distance transversally to the axis defined by the adjusting stud causes, in one direction, the movement of the retaining body member and the retaining spring towards the adjusting stud, with the consequent fixation of the position occupied by the adjusting stud under the combined action of the retaining threads formed thereon, while rotation of the shaft in the opposite direction causes the retaining body member and the retaining spring to move away from the adjusting stud, thereby releasing it from the combined action of the retaining threads; an outer radial extension of the actuating shaft which suitably dimensioned and shaped is designed to facilitate actuation of the retaining means; and an abutment formed externally on the surface of the main body member facing the outer radial extension of the actuating shaft designed to fix the position of said outer radial extension in which the position of the adjusting stud is fixed.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.